Building a deck over a waterproof membrane

Find out more about the different options available for installing a floating deck or tiles over a waterproof membrane.

If you take the time to carry out some research you will find a variety of options available to you for creating a decking or tiles solution to be installed over a waterproof membrane, with each one varying in cost and effectiveness. With membrane decks being one of the most common causes for leaking buildings issues it is important that you choose carefully the solution you wish to use and that you understand the advantages and disadvantages of each system.

Trafficable membrane

A trafficable membrane can of course be very lightweight and the installation cost may seem very low initially. However some systems will require many coatings to maintain the water integrity and it may not always be slip-resistant compliant especially in public spaces.

It is also likely that you will not end up with a level surface which will affect the layout of your furniture if you were to include some in your outdoor space, also consider the flooring will probably in time suffer damage from the feet of the furniture items.

Tiles on deck jacks pedestals

If you opt for a tiles solution you would end up with a very hard wearing surface, relatively easy to remove when membrane inspection is required.

One thing to bear in mind is the high cost and heavy weight of good quality concrete structural tiles, probably not the best solution for renovation work on an existing waterproof membrane that may not have been engineered to handle such heavy loads. Once the tiles have been put into place it also leaves very little room for ventilation which could potentially damage the membrane.

It is also worth considering the temperature the tiles can reach when exposed to sunshine, not an ideal surface for an environment with children.

Timber decking screwed on floating removable deck frame

With timber decking you will of course end up enjoying the aesthetics of natural wood if the high maintenance required is carried out on a regular basis. Some people also enjoy timber decking on their balcony as it can provide that outdoor feel to the space.

However, decks constructed in panels are a theoretical concept, not a practical solution, especially when soaking wet after our typical British weather. A standard 2-3mm gap between timber boards soon closes up to nothing once they have absorbed moisture from the rain and increased in size, stopping the correct amount of ventilation to reach underneath the decking surface.

Inspection when required would also turn out into a very expensive job, with the boards needing to be un-screwed from the sub-frame, most likely damaging them and not looking the same when installed back down, not mentioning the installation costs you would face if you required help with the dismantle and installation afterwards, and of course replacement boards if they were to get too damaged to be re-used.

One last thing to bear in mind if considering this option is the purpose of a sub-structure, mainly to provide a solid and stable structure for the boards to sit on, but joists can be very unstable when unrestrained.

Resortdeck composite decking with Qwickbuild aluminium sub-frame

Our product range is the only solution globally to offer a complete deck over waterproof membrane package.

The composite decking boards and aluminium sub-frame are 100% unaffected by moisture so will never change in size, reassuring customers that the gap in between the boards will always be the same and the correct amount of ventilation will always be in place. Also with the boards fixing to the sub-frame using innovative stainless steel clips instead of screws, the boards are never permanently fixed to the structure which results in easy inspection of the membrane and cleaning of the downpipes when required, without damaging any of the structure.

The qwickbuild decking sub-frame is very light weight and is pre-fabricated in our workshop to made-to-measure kits, easily slotted into place once on site, slashing down installation times and making the job a lot easier without risking damaging the membrane. This also results in more flexibility with the installation as the products are not weather dependent, providing a clean and fast service.

When using our package solution you can be assured that your surface will be safe and level, with the deck being flush with the internal area and the aluminium frame provide a straight and secure surface to lay the boards.

One thing to consider with this option is if there are any curved edges to your design, this could potentially take slightly longer to manufacture and install than a simple straight edge, but once on site the process will be just as easy, fast and clean.

Published: 3rd November 2015

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